Variable speed governor

ABSTRACT

A speed control system for an internal combustion engine having a variable speed throttle includes an operator input control member connected through suitable linkage to vary the setting of the variable speed governor and includes a balance mechanism having spring means operating in opposition to the reactive forces of the governor for providing a relatively uniform control feel over the range of the operator control member.

BACKGROUND OF THE INVENTION

The present invention relates to control means for internal combustionengine and pertains particularly to a governor control linkage forinternal combustion engines equipped with variable speed governor.

Many industrial vehicles are powered by engines of the internalcombustion piston type. Such internal combustion engines employ mixingand metering devices for metering the fuel to the combustion chambers.The flow of fuel to the combustion chamber frequently determines thespeed of the engine. Such metering devices may take the form ofinjectors or carburetors.

In order to maintain a substantially constant speed of the engine forvarying loads, a governor is normally employed which is responsive toengine speed for altering the setting of the fuel flow or mixture to thecombustion chambers. Variable speed governors are normally employed invehicles or engines for vehicles which may undergo frequent adjustmentby the operator in the speed of the engine.

The governor setting which determines the engine speed is set by anoperator control element movable by the operator to select settings toestablish a predetermined setting for the governor. The governor mayemploy numerous devices such as centrifugal weights or the like whereinthe position of the weight is determined by a force acting thereon inaddition to the speed of the engine. With such governors the forcerequired for establishing a selected setting increases with increasingengine speed.

Many vehicles such as industrial lift trucks and the like employimplements which require precise and easily controllable manipulation bythe operator. It is desirable for this reason that the controls of thevehicle be substantially uniform in feel throughout its control range.This is especially so of the throttle or speed control of the vehicle,especially when precise control of the engine speed is frequentlyrequired.

It is therefore desirable that the uneven and excessive force requiredon the operator control element be eliminated, if possible. Accordingly,the present invention is directed to this end.

While the applicants are not aware of any prior art recognition of thisproblem or any proposals for solving the problem, the following priorart is of interest in regards to governor control in general: U.S. Pat.Nos. 2,716,397, issued Aug. 30, 1955 to Heinish; U.S. Pat. No.3,130,599, issued Apr. 28, 1964 to Haas; and U.S. Pat. No. 3,157,167,issued Nov. 17, 1964 to Walker, et al.

SUMMARY AND OBJECTS OF THE INVENTION

A primary object of the present invention is to overcome the aboveproblems of the prior art.

Another object of the present invention is to provide improved controlmeans for a variable governor controlled internal combustion engine.

A further object of the present invention is to provide an operatormanipulated linkage control system for controlling governors andincluding counterbalancing means for substantially evening out andreducing the operator force required over the control range of thesystem.

In accordance with the primary aspect of the present invention, acontrol system including an engine variable speed governor for sensingchanges in engine speed from a preselected setting and controlling thespeed of the engine to correspond to the setting and an operator controlelement connected to the governor and movable over a control range forvarying the control setting of the governor includes balance meansconnected to the operator control element for acting in opposition toreactive forces of the governor for establishing a substantiallyconstant force for the operator control element over at least a majorportion of the control range.

BRIEF DESCRIPTION OF THE DRAWING

The above and other objects and advantages of the present invention maybecome apparent from the following description when read in conjunctionwith the drawings wherein:

FIG. 1 is a perspective view of a portion of a vehicle including acontrol system embodying the present invention; and

FIG. 2 is a side elevational view of a portion of the control linkage ofFIG. 1.

DETAILED DESCRIPTION

Turning now to FIG. 1 there is illustrated a portion of a vehicle suchas a lift truck incorporating the present invention. The vehicle, asillustrated in FIG. 1, includes a prime mover such as an internalcombustion engine of the piston type 10 which transmits power by way ofa standard transmission of any suitable type compatible with the speedcontrol system of this invention. In the embodiment illustrated, thetransmission is of the hydrostatic type comprising a variabledisplacement pump 11 which transmits power by way of hydraulic fluid inlines 12 and 13 to one or more hydraulic motors 14 which are connectedfor driving powered wheels 15 of the vehicle. If so desired, the pumpand motor could be housed in the same case in a conventional manner.

The velocity and direction of the vehicle is selected by the operator byan operator input means or element such as a rocking foot pedal 16 whichis connected by suitable linkage means for simultaneously operating boththe displacement of the pump of the hydrostatic transmission and thegovernor setting for controlling the speed of the internal combustionengine 10. The pedal 16 is pivotally mounted for rocking motion ineither direction from a neutral position and connected by a link 17 toan arm 18 of a rotary shaft 19. The shaft 19 is mounted in spacedbearings in brackets 20 for rotary movement in response to rockingmovement of the pedal 16. The motion transmitted to the shaft 19 istransmitted by suitable linkage including a link 21 connected to an arm22 for controlling the position of valve means 23 which controls thedisplacement of the swash plate (not shown) of standard pump 11.

The arrangement is such that pivotal movement of the pedal 16 in eitherdirection from neutral will result in movement of the swash plate ofpump 11 in either direction from its neutral position therebyestablishing the direction of movement of the vehicle with the amount ofdeflection or depression of pedal 16 determining the speed of thevehicle. The link 21 preferably includes a lost motion linkage such thatthe pedal 16 may be further depressed after full displacement of thetransmission control valve is achieved. This pedal 16 is connected bythrottle linkage to be described so that further depression of the pedalwill increase the engine speed after the transmission has achieved fulldisplacement.

A creeper pedal 24 is connected in a suitable manner through linkage 25to means such as a vent valve within the valve housing 23 for overridingthe control thereof by the pedal 16. This operates to disable thetransmission of the vehicle to enable the engine thereof to be revved upto full speed without the transmission operating to thus increase thepower available for operating the implements at higher speed.

The foot pedal 16 is connected also to the throttle linkage such thatthe engine and transmission may be both manipulated by a single foot ofthe operator.

The engine control linkage includes an arm 26 extending outward fromshaft 19 and first and second links 27 and 28 connected to the outer endof arm 26 and respectively to arms 29 and 30 which are rotatably mountedon a rotatable shaft 31. The shaft 31 includes a pin 32 extendingtherethrough which is normally engagable by one or the other of pins 33on arm 29 or 34 on arm 30. The shaft 31 is suitably journaled in abearing on a bracket 35 and includes a bellcrank 36 connected to rotatetherewith.

A link or control rod 37 of a throttle control means is pivotallyconnected to one arm of bellcrank 36 and extends through a bore 38 witha loose fit on a block 39 secured to a governor control arm 40 which isconnected in the usual manner to vary the setting of the governor 41.The governor 41 is of a conventional design and responsive to the speedof the engine and to the selected settings of the governor controlelement or arm 40 as is established by the operator input controlelement.

Force from the operator control element by way of link 37 is applied tothe arm 40 by means of a tension spring 42 connected at one end to abracket 43 on arm 40 and at the other end to an adjustable bracket 44 onlink or rod 37. The bracket 44 may be moved along the rod 37 to adjustthe tension in spring 42. The sliding fit of the rod 37 in bore 38insures that force is transmitted from the rod 37 by way of spring 42 tothe governor control arm 40. Thus the governor control arm is free tomove in response to governor control as well as the force appliedthrough spring 42. The governor control arm 40 is connected to throttlecontrol means comprising a throttle link 45 pivotally connected to anarm 46 on a carburetor 47 for controlling the throttle valve of thecarburetor. Control of the throttle valve controls the flow of fuel orfuel mixture into the engine combustion chambers and thus the speed ofthe engine. A spring 48 is connected at one end to a stationary bracket49 and the other end to a bracket 50 on rod 52 for biasing thecarburetor control arm 46 toward its minimum speed position.

It will be appreciated that the linkage assembly including links 27-36,forming an operator control input means along with elements 16-19,comprises a one-way linkage of a multi-directional inputsingle-directional output linkage arrangement such that either directionof movement of the operator pedal 16 results in a movement in a singledirection of the rod 37 from its zero or neutral displacement position.Thus either direction or movement of the control pedal 16 increases thegovernor setting of the governor 41 for increasing the engine speed ofthe engine 10. It will also be appreciated that in view of the springmeans 42 and the force necessary to be applied to the governor mechanismthat the force requirements of pedal 16 increases as it is displacedfrom its neutral position.

Turning now to FIG. 2, there is illustrated a balance means or mechanismwhich is designed to partially offset this force increase and to providea fairly uniform pedal force over the major portion of the control rangeof the throttle linkage.

The balance mechanism in accordance with the present invention comprisessuitable opposing force means comprising a spring 51 of the tension typeconnected at one end by a pin 52 to the second arm 36b of the bellcrank36. The spring 51 is connected at its opposite end by means of suitableadjusting means such as an eyebolt 53 extending through a bracket 54which is secured in a stationary manner to a suitable portion of avehicle. A pair of jam nuts 55 and 56 serve to adjust the eyebolt 53along its length and likewise to adjust the tension in the spring 51.

As best seen in FIG. 2, the spring 51 is biased by a fixed cam member 57which is secured in place and adjustable in its angular position bymeans of the bolt 58 or the like.

It will be seen that the spring acts on arm 36b of the bellcrank 36 inopposition to the opposing force acting on link or arm 36a by link 37 byway of spring 42. It will be appreciated that the position of the fixedcam member 57, the pivot axis 59 of bellcrank 36 and the pin position 52of arm 36b will determine the effective moment or torque acting torotate the bellcrank 36. Thus, the direction of action of the spring 51on pin 52 can be varied by means of rotation of cam 57. That isespecially the direction of action at its neutral position. The neutralposition is determined by stop means comprising a screw or the like 60extending through a bracket 61 with suitable jam nuts 62 and 63 foradjusting the position of the head of the screw or bolt 60. Theorientation of the lever/spring assembly at start is thus determined bythe setting of this stop means for abutment by arm 36a of the bellcrank36.

It will be appreciated that when the bellcrank 36 rotates in clockwisedirection, the moment arm between pivot pin 59 and pin 52 increaseswhile at the same time the tension in spring 51 decreases so that theincrease in moment arm compensates for the decrease in force or tensionin spring 51. The action of this mechanism is such as to oppose thereactive forces on link 37 by the governor control arm 40 so that theseforces are somewhat balanced over the range of movement of the controlpedal or the major portion of the range of movement of control pedal 16.It will be appreciated of course that a certain amount of bias will beneeded to return the linkage to the neutral or zero position. With thepresent invention, however, the amount of force necessary to move thelinkage or governor control from its neutral position to its maximumposition will be somewhat uniform over at least a major portion of therange of movement. This gives the operator of the vehicle a much betterfeel of the vehicle such that the engine speed and transmissiondisplacement can be more precisely and effortlessly controlled.

While the present invention has been described and illustrated by meansof a preferred embodiment, it is to be understood that numerous changesand modifications may be made therein without departing from the spiritand scope of the invention as defined in the appended claims.

What is claimed is:
 1. A control system including in combination anengine variable speed governor for sensing changes in engine speed froma preselected setting and controlling the speed of the engine tocorrespond to said setting;operator control input means connected tosaid governor and movable over a control range for varying the controlsetting of said governor; and balance means connected to said operatorcontrol input means for acting in opposition to reactive forces of saidgovernor against said operator control input means for establishing asubstantially constant force for said operator control input means overa major portion of said control range comprising spring means acting inopposition to said reactive forces and cam means engaging said springmeans and altering the normal variations in tension of said spring overits normal range of displacement.
 2. The control system of claim 1wherein said operator control input means comprises linkage means forselectively preloading a spring connected to said governor forestablishing said preselected settings.
 3. The control system of claim 1wherein said spring means comprises a tension spring; andtensionadjusting means for adjusting the tension in said tension spring.
 4. Thecontrol system of claim 1 wherein said operator control input meanscomprises a rocking foor pedal mounted for rocking movement in eitherdirection from a neutral position, linkage means connecting said footpedal to a governor control element of said governor, and means formoving said governor control element in a single direction from aneutral position upon movement of said foot pedal in either directionfrom its neutral position.
 5. A control system in combination with acontrol means for an engine comprisingoperator control input meansincluding a pivoted bellcrank having first and second arms, spring meansconnected between said control means and the first arm of said bellcrankfor biasing said bellcrank in a first pivoted direction, and balancemeans, comprising a tension spring and cam means engaging said tensionspring for applying a force thereagainst, connected to the second arm ofsaid bellcrank for biasing said bellcrank in a second pivoted directionopposite to said first pivoted direction against and in balancingrelationship with respect to the biasing force of said spring means.